Wind Energy

3 Time Domain Comparison Using Constrained Wind Fields 17
centre) and is used in combination with Flex5. The other applies a Cartesian
grid (15 by 15) and produces wind fields which can be read by Bladed. In
order to investigate the influence of the number of measuring points several
configurations of anemometers (ranging from 1 to 11) have been considered.
In Fig. 3.1 two of the considered configurations are shown.
One of the simulated wind fields can be appointed to be the “measured”
wind field. The reduced scatter in the constrained wind time series is shown
in Fig. 3.2. The shape of the time series gets more fixed (determined by the
measured wind speeds). Unconstrained wind fields will average out to straight
horizontal lines; the variance will be uniform over the rotor plane.
110
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−50 −40 −30 −20 −10 0 10 20 30 40 50
110
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Fig. 3.1. The applied rectangular grid for the spatial wind fields and the locations
of the anemometers of 2 of the considered configurations: 1 (left) and 7 (right);
radius R and 2/3R are also indicated
Vertical direction
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−40 −30 −20 −10 0 10 20 30 40
Lateral direction
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0 10 20 30
Time (s)
40 50 60
Fig. 3.2. Left: contour plot of the variance of the spatial constrained wind fields
(averaged over time) over the rotor plane. Right: the mean (and plus/minus one
standard deviation) of 30 constrained (7 anemometers) simulations; 17 m below the
rotor centre